Trinamool Congress leader Mohammad Iqbal, the prime suspect in the Garden Reach police officer killing incident last month, was arrested on Thursday from Bihar, police said.
"Iqbal has been arrested from Dehri-on-Son about an hour ago. He will be brought to Kolkata," Additional Director General (CID) Shibaji Ghosh told IANS.
"He will be produced before a court there and we will seek his transit remand from the court," added Ghosh.
The Trinamool councilor and chief of the borough committee was seen at the spot of the incident, threatening a policeman and mobilising his supporters during the Feb 12 clash between student activists in city's Garden Reach area.
Special branch officer Tapas Chowdhury was shot dead in broad daylight while trying to control clashing Trinamool Congress and Congress student activists at the Harimohan Ghosh College.
The violence in the college erupted over the issue of picking up nomination forms for the students' union election.
Iqbal, who has been charged with rioting, attempt to murder and certain sections of the Arms Act by police, was in hiding following the incident. The CID which subsequently took over the investigation from the city police has been on hot pursuit for Iqbal.
Video footage aired by television channels showed Iqbal standing beside Sheikh Subhaan, the man who was caught on TV firing the bullet that allegedly killed the policeman.
Soon after the video footages, Trinamool leader and state Urban Development Minister Firhad Hakim defended Iqbal saying "he was not involved".
Hakim's "shielding" of Iqbal attracted severe criticism from several quarters with the opposition Left Front demanding his removal as a minister, accusing him of being involved in the incident.
Twelve people, including Subhaan, an aide of Iqbal, are currently behind bars.
Following the police's "inability to arrest the culprits", Chief Minister Mamata Banerjee removed city Police Commissioner R.K. Pachnanda, a move which was disapproved by Governor M.K. Narayanan.
The Congress has demanded a Central Bureau of Investigation (CBI) probe into the matter.